Datasheet

Data Sheet ADA4500-2
Rev. A | Page 21 of 24
POWER-ON CURRENT PROFILE
The ADA4500-2 powers up with a smooth current profile, with
no supply current overshoot (see Figure 63). When powering up
a system, spikes in the power-up current are undesirable (see
Figure 64). The overshoot requires a designer to source a large
enough power supply (such as a voltage regulator) to supply the
peak current, even though a heavier supply is not necessary once
the system is powered up. If multiple amplifiers are pulling a
spike in current, the system can go into a current limit state and
not power up. This is all avoided with the smooth power up of
the ADA4500-2.
10617-107
5
0
1
2
3
4
0
2 4 6
8 10 12 14
16 18 20 22
24 26 28
30
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
TIME (µs)
60
0
5
10
15
20
25
30
35
40
45
50
55
Figure 63. I
SY
and V
SY
vs. Time for ADA4500-2 with No Spike
10617-106
5
0
60
0
5
10
15
20
25
30
35
40
45
50
55
1
2
3
4
0 2 4
6 8
10
12 14 16 18 20 22 24 26 28 30
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
TIME (µs)
Figure 64. I
SY
and V
SY
vs. Time with a Power-Up Spike
For systems that are frequently switching off and on, the power-
up overshoot results in excess power use. As the amplifier switches
off and on, the power consumed by the large spike is repeated
on each power-up, increasing the total power consumption by
magnitudes. As an example, if a battery-powered sensor system
periodically powers up the sensor and signal path, takes a reading,
and shuts down until the next reading, the ADA4500-2 enables
much longer battery life because there is no excess charge being
consumed at each power-up.